What are the Components of a Solar Panel?

Solar panels are energy efficient and produce environmentally friendly energy. They use a renewable energy source –solar power that we have an endless supply of. These panels are made from several materials and components. The main component of most solar photovoltaic panels is crystalline silicon wafers. Almost 95% of solar panels use silicon to create semiconductors. The rest of the 5% use in-development and experimental technologies such as organic photovoltaic cells. The electricity you get through the solar panels is derived from semiconductors. They come in contact with sunlight, and the electrons present in the semiconductors become loose. It produces electricity, and the process is known as the photovoltaic effect. However, the photovoltaic cells are not the only component that helps provide to your house. Other components such as wiring, metal, glass, and plastic produce power. The solar cells used in solar panels are ideally sensitive to sunlight. To protect these solar cells, solar panels have a glass layer along with an anti-reflective coating over them. However, the coating and glass layer still lets the sunlight pass into the cells. The solar panel system is mounted on a polymer or plastic frame during the installation process. They can either be ground-mounted or installed on your rooftop.

What Are The Parts Present In A Solar Panel?

As mentioned above, solar panels are made from several components. The below section provides an overview of those components. Silicon Solar Cells Silicon solar cells are the components that use the photovoltaic effect to convert solar power into electricity. The structure of the solar cells is like a matrix and is bounded together between glass panels. These silicon solar cells create electric charge by interacting with the glass wafer sheet. Metal Frame The metal frame of a solar panel is ideally made from aluminium and helps with several things. It prevents the solar panel from getting damaged from dangerous situations or harsh weather conditions. The frame is also helpful in mounting the solar panel at your preferred angle. Standard 12V Wire The 12V Wire helps in regulating the energy that is transferred to your inverter. It helps in making the solar panel system more efficient and sustainable. Bus Wire The solar silicon cells are connected parallel to the panels using the bus wires. They have a thin solder layer that helps in soldering. Moreover, the bus wires are thick enough to pass on the electric currents. Glass Sheet The glass sheet present in the solar panels is usually six to seven millimetres thick. This is quite thin, but they help protect the silicon solar cells present in the solar panel system.

How Are Solar Panels Made?

The solar panel manufacturing process starts with the creation of silicon cells. This process includes melting the silicon and them mixing it with other supporting elements. Then different sheets are cut to turn them into component cells. The process involves mass production as well as laser cutting. These finished cells are protected using a layer of plastic or glass. After creating the solar cells, they are connected at the right configuration, shape, and size. For doing this, these are soldered to the solar panel’s base. This base is made from a conductive metal, which is essential for electricity production. The next step is to connect the system to a polymer frame. This holds the system and insulates all the electrical components. It covers all the components using a protective glass layer. The final step involves boxing all the panels and sending them to the installers.

Is The Manufacturing Process Of Solar Panels Environment Friendly?

Solar energy is a clean source of energy, but the manufacturing process is not as clean. There have been severe improvements in the solar panel manufacturing process, ensuring less environmental pollution. According to an academic study, there has been a downward slope in the environmental impact of solar panel manufacturing between 1975 and 2015. This downward slope has not stopped in years, and manufacturers have come up with more environmentally friendly solutions. Solar producers are trying to find environment-friendly solar production and materials. They are also searching for ways to recycle the panels and their components. This minimizes the harsh impacts that solar panels have on the environment. That being said, the production of solar panels emits harmful carbon dioxide into the environment. This is what renewable energy sources are trying to curb. The same happens for other renewable energy source systems such as wind turbines and power plants. However, since solar panels have extended longevity, the environmental impact has been divided over the years.

Is It Dangerous To Live Nearby A Solar Farm?

A solar farm is a large piece of land with several solar panels that help generate electricity on a large scale. Solar farms do not emit any toxic chemicals, noise, or pollution that would cause a hazard to the environment. The hazardous materials that are present in the solar panels are contained within them. They are not emitted during usage, which leads to the production of clean energy. However, the issue arrives when the solar panels are being disposed of or recycled. It should be done in an area that does not have a livelihood nearby.

What Are The Toxic Materials Present In A Solar Panel?

Certain materials present in the solar panels are very toxic to the environment and people. These include selenium, copper, arsenic, cadmium telluride, or hexavalent chromium coating. However, these materials are only toxic during the manufacturing of solar panels. Once the solar panels are taken into operation, these materials have no impact. This is because the materials are contained within the solar panel. It does not get activated when the panel comes in contact with sunlight. Therefore, the energy we get is clean, efficient, and sustainable.

What Are Solar Panels Made Of? - Solar Panels Network

Have you ever wondered what’s inside a solar panel that makes it convert sunlight into electricity? Understanding the structure and materials of a solar panel helps you appreciate why they last 25 to 30 years, why modern panels are more efficient than older models, and what you’re actually purchasing when you invest in solar for your home.

A typical solar panel is a sophisticated assembly of multiple layers, each serving a specific purpose. At the heart is the photovoltaic cell: usually made from silicon, either monocrystalline or polycrystalline. Surrounding and protecting the cells are layers of glass, plastic, aluminium, and wiring that work together to create a durable, weather-resistant module. In this guide, we’ll dissect a solar panel and explain the function of each component.

The materials used in solar panel manufacturing have evolved significantly since the early 2000s. Modern panels are more efficient and more reliable because of advances in silicon purification, encapsulation technology, and frame design. Whether you’re considering a new installation or simply want to understand the technology, this breakdown will help you see why solar panels have become such a trusted form of renewable energy in the UK.

Contents

1 Key Takeaways
2 Solar Panel Structure: Layer by Layer
3 Silicon Solar Cells: Monocrystalline vs. Polycrystalline
4 Glass and Anti-Reflective Coating
5 EVA Plastic Encapsulation
6 Silicon Cell Structure and Junction Layers
7 The Backsheet: Weather Protection and Insulation
8 The Aluminium Frame
9 Wiring, Busbars, and Electrical Components
10 The Junction Box and Bypass Diodes
11 Case Study: Understanding Panel Degradation Through Component Analysis in the South East
12 Expert Insights From Our Solar Panel Installers About Panel Materials
13 Frequently Asked Questions
14 Summing Up

Key Takeaways

Solar panels consist of silicon solar cells, glass, aluminium frame, EVA plastic encapsulation, junction box, and wiring
Monocrystalline silicon cells are more efficient than polycrystalline but slightly more expensive to produce
The glass front layer is typically tempered glass up to 4mm thick, designed to withstand weathering and impact
EVA (ethylene vinyl acetate) plastic encapsulates the cells and protects them from moisture and oxidation
The backsheet is a weather-resistant polymer layer that insulates and protects the cell assembly from below
Aluminium frames distribute the panel’s weight across mounting points and protect the edges of the glass
Modern panels use copper wiring and multi-busbars to maximise electrical conductivity and reduce losses
The junction box contains bypass diodes that allow current to flow around shaded cells and protect the panel

Solar Panel Structure: Layer by Layer

A solar panel is built up from multiple layers pressed together under heat and pressure during manufacturing. Understanding each layer helps explain why panels are so durable and efficient.

Starting from the front, the first layer you see is tempered glass. This is not ordinary window glass: it’s been specially treated using a tempering process that makes it stronger and more impact-resistant. Below the glass is a thin anti-reflective coating that reduces light reflection and allows more sunlight to pass through to the cells below.

Next comes the encapsulation layer, typically made of EVA (ethylene vinyl acetate) plastic. This clear material holds the silicon cells in place and seals out moisture. EVA is chosen because it’s transparent, flexible, and excellent at bonding to both glass and silicon.

In the centre of the panel are the silicon solar cells themselves, arranged in a grid pattern (typically 60 to 72 cells for residential panels). These cells are connected by thin copper ribbons called busbars that collect the electrical current generated by each cell.

Below the cells is another layer of EVA plastic, identical to the front layer, which provides further moisture protection and structural support.

The backsheet comes next: a thin, multi-layer polymer material that insulates the cell assembly and protects it from weather exposure on the rear side. The backsheet is typically white or black, depending on the panel type.

Finally, the aluminium frame wraps around the entire assembly, protecting the edges and providing mounting points for attachment to your roof.

Silicon Solar Cells: Monocrystalline vs. Polycrystalline

The silicon solar cell is where the magic happens: where photons from sunlight knock electrons loose from silicon atoms, creating an electrical current. Nearly all residential solar panels use one of two types of silicon cell: monocrystalline or polycrystalline.

Monocrystalline silicon cells are cut from a single large crystal of silicon. This uniform crystal structure means electrons can flow more easily through the material, making monocrystalline panels more efficient. A typical monocrystalline cell converts about 20 to 22% of incident sunlight into electricity. Modern high-efficiency cells from brands like Sunpower and Maxeon achieve efficiencies above 22%.

Monocrystalline cells are instantly recognisable: they have a uniform dark (usually black or dark blue) colour with clean, square edges. They are the premium choice for residential installations where roof space is limited.

Polycrystalline silicon cells are made from molten silicon that is cooled and solidified into a block. The crystal structure is less uniform than monocrystalline, with multiple crystal boundaries. This makes polycrystalline cells slightly less efficient, typically 17 to 19%, because electrons encounter more resistance as they flow through the different crystal regions.

Polycrystalline cells have a distinctive speckled appearance with a medium blue colour. They are cheaper to produce than monocrystalline because the manufacturing process is simpler. For larger roofs where space is not a constraint, polycrystalline panels offer excellent value.

In the UK market, monocrystalline panels have become dominant because of their higher efficiency and improving cost competitiveness. Most installers now recommend monocrystalline for residential installations.

Glass and Anti-Reflective Coating

The front glass of a solar panel is not ordinary window glass. It’s tempered or toughened glass that can withstand impact, hail, and thermal stress. UK manufacturing standards (such as those defined by IEC 61215) specify that panel glass must resist hail impacts up to 25mm at terminal velocity and thermal cycling from -40 degrees Celsius to +85 degrees Celsius.

Typical panel glass is 3 to 4mm thick and is treated with a low-iron composition. Low-iron glass is more transparent than ordinary soda-lime glass, allowing more light to reach the silicon cells. The front surface of the glass has a textured or slightly rough texture that helps trap light and prevent it bouncing straight back into the atmosphere.

Many modern panels include an anti-reflective coating applied to the glass surface. This coating (usually silicon nitride or a similar compound) reduces the amount of light reflected at the glass interface. Without an anti-reflective coating, about 3 to 4% of light is reflected away. With the coating, reflection drops to less than 1%. This seemingly small improvement translates to about 2 to 3% more power generation over the panel’s lifetime.

The glass also serves as the primary weather barrier, protecting all the components inside from rain, snow, frost, and UV radiation. The durability of panel glass is why solar panels can remain outdoors in all UK weather conditions for 25 years or more with minimal degradation.

EVA Plastic Encapsulation

EVA (ethylene vinyl acetate) is a copolymer plastic that looks and feels like flexible rubber. It is used in two layers within a solar panel: one sandwiched between the front glass and the silicon cells, and another between the cells and the backsheet.

EVA serves several critical functions. First, it holds the cells in place during manufacturing and throughout the panel’s life, preventing them from shifting or cracking under thermal stress or vibration. Second, it seals out moisture: the EVA layer prevents water vapour from entering the panel and corroding the metal contacts on the cells. Third, it provides electrical insulation, preventing short circuits between cells and the metal frame.

EVA is chosen for these roles because it bonds well to both glass and the silicon cells, it remains flexible across a wide range of temperatures (from -40 to +85 degrees Celsius), and it has excellent chemical stability. When EVA is exposed to UV light during manufacturing (after installation, it’s protected by the glass), it becomes slightly more rigid and yellow, but this does not affect its function.

The quality of EVA and its processing (known as the “cure” process where EVA is heated under pressure during manufacturing) has a significant impact on panel longevity. Premium panel manufacturers invest in high-quality EVA and precise curing, which is one reason their panels often have longer warranties (25 to 30 years vs. 20 to 25 years for budget panels).

Silicon Cell Structure and Junction Layers

Within each silicon solar cell is a very thin p-n junction, where a layer of positively doped silicon sits adjacent to a layer of negatively doped silicon. This junction is the heart of the photovoltaic effect. When a photon from sunlight strikes an electron in the silicon lattice, it gives the electron enough energy to jump free. The p-n junction’s electric field then separates the free electrons from the positive holes, directing electrons toward the negative terminal and holes toward the positive terminal. This creates an electrical current.

The p-n junction in a modern solar cell is extraordinarily thin, often just 0.3 to 0.5 micrometres. Creating such a precise junction requires sophisticated doping techniques where boron and phosphorus atoms are diffused into the silicon at high temperatures.

On the front surface of the cell is a metal grid of busbars and finger contacts. These are thin lines of silver or copper that collect the current generated throughout the cell and channel it toward the junction box. The pattern of busbars and fingers is carefully designed: too sparse and they create resistive losses; too dense and they block sunlight from reaching the silicon beneath. Modern designs use up to 5 or more busbars to reduce losses, compared to older designs with just 2 to 3 busbars.

The back surface of the cell has a full metal contact layer, usually aluminium, that allows current to flow out of the cell. In premium monocrystalline cells, the back contact is carefully patterned to allow light to reflect off it and reach the silicon again (this is called “back-contact” or PERC cell design), improving efficiency by another 1 to 2%.

The Backsheet: Weather Protection and Insulation

The backsheet is the layer on the rear side of the panel that faces away from the sun. It serves as the primary insulator and weather barrier for the components on the back side of the panel (cell contacts, wiring, junction box).

Backsheets are typically 300 to 350 micrometres thick and are composed of multiple layers of fluoropolymer or polyester materials. A common backsheet design has three layers: a polyester layer for mechanical strength, a fluoropolymer layer for UV protection, and an outer polyester layer for water resistance.

The backsheet must withstand the same thermal cycling and UV exposure as the front glass. It must be electrically insulating (typically rated at 5,000 to 10,000 volts) to prevent short circuits and to meet electrical safety standards.

Backsheets are available in white, black, or transparent (clear) versions. White backsheets have higher albedo (reflectivity) and reduce the temperature of the panel slightly, improving efficiency in hot climates. Black backsheets are more aesthetically pleasing and are standard in residential installations. Transparent backsheets are used in some bifacial panels that capture light reflected from a light-coloured roof or surface below.

The quality and durability of the backsheet material is a key differentiator between premium and budget panels. Poor-quality backsheets can fail prematurely due to UV degradation, leading to moisture ingress and cell oxidation. This is why premium manufacturers often warranty their backsheets for the full 25 to 30 year lifespan, whilst budget panels may only warranty the backsheet for 10 to 15 years.

The Aluminium Frame

The aluminium frame that borders the panel serves multiple purposes: it protects the edges of the glass, distributes the panel’s weight across mounting points, provides structural rigidity, and ensures the glass and backsheet remain sealed and protected.

The frame is typically 40 to 50mm tall and is fabricated from extruded aluminium alloy (usually 6063 or 6061 alloy for strength). The cross-section of the frame is designed with internal ribs and channels that provide stiffness whilst keeping weight low. Standard residential panels (about 2 metres by 1 metre) weigh 18 to 22 kilograms, with the frame accounting for about 10 to 12% of the total weight.

Four corner brackets (called end-pieces or corner connectors) join the frame together at right angles and provide the primary mounting points. These brackets are drilled with holes sized to fit M8 or M10 bolts that attach to the roof-mounting system.

The frame seals the edge of the panel with a rubber gasket that runs around the interior perimeter. This gasket prevents moisture from seeping between the glass, the backsheet, and the frame. High-quality gaskets remain flexible across the full temperature range and do not degrade due to UV or ozone exposure.

Anodised aluminium frames (treated with an electrochemical layer) resist corrosion better than untreated aluminium. Most panels use anodised frames, especially for installations in coastal or high-humidity areas where salt spray and moisture accelerate corrosion.

Wiring, Busbars, and Electrical Components

Inside the panel, silicon cells are connected together in series using thin copper ribbon called busbar. A typical 60-cell panel is arranged in two strings of 30 cells each, with each cell contributing about 0.6 volts. The busbars join cells in series so their voltages add up: 30 cells in series produce about 18 volts (before the junction box converts this to standard output).

Modern panels use multi-busbar designs with 5 or more busbars per cell instead of traditional 2 or 3-busbar designs. Multi-busbars reduce resistive losses by shortening the distance that current travels across each cell, improving efficiency by about 1%.

The busbars are coated with solder (typically lead-free tin-copper solder in modern panels) to ensure good electrical contact with the cell. The solder joint must be strong and corrosion-resistant to last the panel’s 25-year lifetime.

From the busbars, output wires (typically 4mm2 copper conductor insulated in UV-resistant plastic) run to the junction box at the back of the panel.

The Junction Box and Bypass Diodes

The junction box is a small plastic enclosure mounted on the back of the panel where the output wires terminate and are connected to external cabling. Inside the junction box is a bypass diode (or multiple bypass diodes, one per string of cells).

The bypass diode serves a critical function: it allows current to bypass a shaded or malfunctioning cell string, preventing that string from becoming a resistive load on the rest of the panel. Without bypass diodes, a single shaded cell could dramatically reduce the output of the entire panel. With bypass diodes, only the shaded section is bypassed, and the rest of the panel continues to generate normally.

Bypass diodes are rated for high reverse voltage (typically 200 to 400 volts) and high forward current to handle the full output current of the panel. They must remain reliable across the temperature range of the panel (from -40 to +85 degrees Celsius) and must not introduce significant resistive losses in normal operation.

The junction box also includes terminals where standard 4mm solar connectors are attached. These connectors link the panel to the next panel in the array (in series) or to the inverter and electrical switchgear. Standard MC4 connectors (now phased out in favour of Amphenol-type connectors for safety) are used on most panels installed before 2020.

Case Study: Understanding Panel Degradation Through Component Analysis in the South East

Background

A homeowner in the South East had a 4kW solar system installed in 2005. After 18 years, annual generation had dropped by about 15%, which was more than the expected 0.5% annual degradation rate. The system owner wanted to understand what had happened to the panels.

Project Overview

A solar surveyor visited and physically examined one of the panels from the system. The panel appeared undamaged from the front, but the backsheet showed signs of yellowing and small cracks (delamination) near the bottom edge.

Implementation

The surveyor explained that the panel’s EVA encapsulation had degraded due to a combination of factors: UV exposure, thermal cycling, and possibly insufficient curing during manufacturing (this was common in some budget panels from the mid-2000s). The cracks in the backsheet allowed moisture to enter the panel. Once moisture reached the junction box, it corroded the diodes and solder joints, reducing the panel’s efficiency.

Results

The homeowner decided to upgrade to a modern monocrystalline system using premium panels with enhanced encapsulation and multi-busbar design. The old panels were safely removed and recycled. The new system, with its superior materials (high-quality EVA, robust backsheet, multi-busbar cells), is expected to degrade at the standard 0.5% per year rate and will generate at least 20% more electricity than the original system at year 1.

Expert Insights From Our Solar Panel Installers About Panel Materials

One of our senior solar panel installers with over 14 years of experience says: “The quality of the materials inside a panel makes all the difference to longevity and performance. I’ve seen panels from the early 2000s with degraded backsheets and brittle EVA failing after just 15 to 20 years. Modern panels use much better materials. The EVA curing process is more controlled, the backsheets are thicker and more durable, and the cells have multi-busbar designs that reduce losses. When we recommend a panel, we always check the materials and the warranty. A premium panel might cost 10% more upfront, but you’re investing in 25 to 30 years of reliable generation.”

Frequently Asked Questions

What type of silicon is used in modern solar panels?

Most residential panels use monocrystalline silicon, which is more efficient (20-22%) than polycrystalline (17-19%). Monocrystalline cells are cut from a single silicon crystal, whilst polycrystalline cells are made from molten silicon with multiple crystal regions. Monocrystalline is now standard for residential installations in the UK.

Is the glass on solar panels tempered?

Yes. Solar panel glass is tempered or toughened to resist impact, hail, thermal cycling, and UV exposure. Tempered glass is also low-iron, allowing more light through to the cells. It must meet IEC 61215 standards for durability.

What is EVA and why is it used in solar panels?

EVA (ethylene vinyl acetate) is a flexible plastic used in two layers within a panel to encapsulate the silicon cells. It bonds to glass and silicon, seals out moisture, provides electrical insulation, and remains flexible across wide temperature ranges. EVA quality directly affects panel longevity.

What is the backsheet made of?

The backsheet is a multi-layer polymer (typically 300-350 micrometres thick) made of fluoropolymer and polyester. It insulates the back of the panel, protects components from weather, and prevents moisture ingress. Quality backsheets are critical for long-term reliability.

Why are bypass diodes needed in solar panels?

Bypass diodes prevent shaded or malfunctioning cell strings from becoming a resistive load on the rest of the panel. They allow current to bypass the shaded section, so the rest of the panel continues generating normally. Without bypass diodes, shading on one cell would significantly reduce the entire panel’s output.

What are busbars and why do modern panels use multiple busbars?

Busbars are thin copper ribbons that collect electrical current from each silicon cell. Multi-busbar designs (5 or more busbars per cell) reduce the distance current travels across each cell, lowering resistive losses and improving efficiency by about 1% compared to traditional 2 or 3-busbar designs.

How much does the aluminium frame weigh?

The aluminium frame accounts for about 10-12% of a panel’s total weight. A standard residential panel (2 metres by 1 metre) weighs 18-22 kilograms, with the frame weighing roughly 2-2.5 kilograms. Extruded aluminium alloy provides strength whilst keeping weight low.

Can solar panel materials be recycled?

Yes. Modern recycling facilities can recover up to 95% of panel materials: glass, aluminium, silicon, copper, and other metals. Recycled materials feed back into new panel manufacturing or other applications, creating a circular economy for solar.

Summing Up

A solar panel is a sophisticated assembly of precisely engineered materials working together to convert sunlight into electricity for 25 to 30 years. From the tempered glass front and EVA encapsulation to the multi-busbar silicon cells, bypass diodes, and robust backsheet, every component plays a vital role in durability and performance. Modern panels benefit from decades of material science advances: better silicon purification, multi-busbar cell designs, and enhanced encapsulation all contribute to higher efficiency and longer lifespan compared to panels from the early 2000s. Understanding these materials helps you appreciate why solar remains such a reliable and cost-effective investment. To discuss which panel materials are best suited to your home and to receive a professional recommendation, contact us for a free quote.

Updated April 2026